1. Field
Aspects of the present invention relate to a method of charging a battery pack and the battery pack.
2. Description of the Related Art
As portable electrical devices such as cellular phones, notebook computers, camcorders, personal digital assistants (PDAs), and other similar portable electrical devices are being developed, secondary batteries are being actively researched.
Such a secondary battery is configured as a battery pack including a battery cell and a charge/discharge circuit. The battery cell is charged or discharged by an external power source or load through an external terminal installed in the battery pack. That is, when the external power source is connected to the battery pack through the external terminal, the battery cell is charged by an external power supplied through the external terminal and the charge/discharge circuit. When the external load is connected to the battery pack through the external terminal, a power of the battery cell is supplied to the external load through the charge/discharge circuit and the external terminal to discharge the battery cell. Here, the charge/discharge circuit is disposed between the external terminal and the battery cell to control a charging/discharging operation of the battery cell.
Generally, in the charging operation of the battery cell, the battery cell is charged at maximal charging current until a power of the battery cell reaches a certain voltage. Then, when the power of the battery cell reaches the certain voltage, the charge current gradually decreases.
However, a case exists wherein the voltage of the battery cell and the charge current decrease at once and subsequently the charge current again increases, i.e., a trickle charge current occurs repeatedly during the charging operation of the battery cell. In such a case, the trickle charge current damages the battery cell or the external power source to and deteriorates safety of the battery cell and/or the external power source.